An electromagnetic valve which has been conventionally known actuates a valve element to open and close a flow path. Such an electromagnetic valve is disclosed in, for example, WO 2013/138144 A1.
WO 2013/138144 A1 discloses an electromagnetic valve that opens a flow path by energizing an electromagnetic coil and actuating a movable core (valve element) in a cylinder. In this electromagnetic valve, the movable core (valve element) having, on its outer peripheral face, an O-ring (seal member) for reducing leakage of a fluid (hydraulic fluid) is held slidably with respect to an inner peripheral face of the cylinder. The movable core also has a biasing member for applying a pressing force to the O-ring, the biasing member being adjacent to the O-ring. In a state in which the movable core closes the flow path, a fluid (hydraulic fluid) accumulated by an accumulator on a high-pressure side (primary side) presses the O-ring with the biasing member through a clearance between the outer peripheral face of the movable core and the inner peripheral face of the cylinder to change the sectional shape of the O-ring. This configuration enhances the contact force (sealability) of the O-ring to the inner peripheral face of the cylinder to further reduce leakage of the high-pressure fluid (hydraulic fluid) toward a low-pressure side (secondary side) through the clearance between the movable core and the cylinder. As disclosed in WO 2013/138144 A1, the accumulator-use electromagnetic valve is provided with the O-ring for reducing leakage of a high-pressure fluid. In general, however, conventional oil path switch valves (solenoid valves) and proportional control electromagnetic valves (linear solenoid valves) are not provided with such an O-ring except for accumulator-use electromagnetic valves.